I don't understand this obsession with running projects for "nothing" and contorting software architecture to do so.
$5/mo for a digital ocean droplet or $50/month for a a beefier VPS (or even dedicated hardware if you know where to look[0]) is not much compared to the normal monthly expenditure of people in tech on average.
If it was all for convenience/efficiency that'd be one thing, but learning "google cloud run" teaches you nothing about system maintenance, limits your understanding of the full stack, and encourages a myopic view of development, all so at some point when Google/AWS/Azure raises the temperature of the water in the pot everyone starts wondering "how did running software get so expensive?".